Nick Clegg was interviewed on Sunday sofa TV this weekend by Andrew Neil. Promising stuff, but political reporters in search of a headline were disappointed. Neil is a well-prepared and combative inquisitor, David Frost with a Taser. But it was dull. A setback for Cleggie then? Not a bit of it, a triumph. He's survived his ordeal and all those policy pitfalls – as Ed Miliband did not when quizzed by Martha Kearney on Radio 4's World at One.

That's the trouble with interviews of all shapes and sizes, as Tory MP Amber Rudd discovered this week. They're a gamble, only more so in politics where the stakes are often higher and sudden death more brutal. The interviewer misunderstands. He/she writes up the frivolous angle. Some brute puts up a savage headline.

Dull but decent is a good policy: Douglas Hurd was a past master, so is Alistair Darling. Both rose to dizzy heights by being as unflashy as someone like George Galloway wasn't.

How much trouble is charming Rudd in after taking the Financial Times around her highly marginal constituency of Hastings & Rye (paywalled link), scene of recurring battles since 1066 – mostly against French raiders or Labour challenges? My hunch would be not much more than she's in already with a majority of 1,993. Rudd is smart and charming, unpaid parliamentary private secretary to George Osborne, a well-connected woman with a bit of fight.

All the same it probably wasn't wise to say she'd been looking for a seat in 2010 ""within two hours of London and I could see we were going to win it". Or dwell on the high proportion of benefit claimants the faded-but-resilient Sussex seaside town has acquired. Or admit: "If the worst comes to the worst it's been a great five years." I find such candour rather endearing, but have learned to mistrust my own reactions as psephology. Some of the FT's below-the-line contributors in Hastings were a bit miffed.

Never mind, Rudd, it was a long and informative article, which will be in Fleet Street's e-files for handy reference. And not too many people in Hastings – or even in Rye – read the FT, alas. On the downside the cheeky LabourList website used it to run a feature which will also be in the e-files: how not to do a gaffe-strewn interview like Rudd. Don't diss the constituency or the voters. That sort of thing. And don't do too much detail. On gay marriage, Rudd remarked: "I don't think they'll still be thinking about anal sex" on polling day. You never know, some censorious voters may well think of little else.

But these are small crosses to bear. A good candidate can make a difference. A one-vote majority is enough. But mostly it is national swings that decide outcomes, though having a low swing against you – "she fought a good campaign" – helps if Rudd ever tries for a safer billet.

In which case Miliband's World at One interview may be better news for Rudd than a chunk of space in the FT. On the local election campaign trail the Labour leader refused to explain how he would cut VAT and low-rate income tax to boost the economic recovery or to confirm (as Ed Balls has done) that borrowing would have to rise in the short term to stimulate the growth UK Plc desperately needs.

That allowed the Tories to say there would be a £28bn black hole in the public finances – shades of Chris Patten and John Major's "tax bombshell" campaign in 1992. The Guardian didn't make much of it, but the Times put it on page one and the Daily Mail helpfully reprinted verbatim his exchanges with Kearney under a "Milishambles" headline. That's now in the e-cuttings too and far more seriously. It hits Miliband where he's vulnerable and where Labour is vulnerable: on management of the economy in tough times when many voters blame the Blair/Brown governments instead of the bankers they failed to supervise properly for the crash of 2008.

Worse, it shows Miliband as ill-prepared, callow even. I don't enjoy pointing this out. But it's an obvious question, one with an obvious and legitimate answer, roughly along the lines of: "Of course, we must borrow more in order to borrow less in the long term. The coalition's austerity programme is clearly self-defeating, Osborne is borrowing much more money than he promised to – or Labour did – because he is squeezing the life out of the economy. All over the developed industrial world – from Tokyo to Paris – have reached the same conclusion."

Any politician – footballer too for that matter – doing an interview should ask him/herself what the interview is for. "What do I want to say, what message to get across?" Also "what do I not want to say or concede?" And "who will read this?" Once clear in one's own head, the interview can safely proceed. When in doubt repeat yourself. It's harder in print (more words) but the stakes are higher on telly.